Filters > D68HPLP


1 Hz to 100 kHz
32 Pin DIP


Pin-out and package data

Ordering Information

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D68HPLP Series
Fixed Frequency
4-Pole Pair
Band-Pass Filters






The D68HPLP Series of small 4-pole-pair fixed-frequency, precision band-pass active filters provide high performance in a compact 32- pin DIP package, with a broad range of fixed center frequencies (fo) from 1 Hz to 100 kHz. Each filter type features a near theoretical amplitude/phase response along with low output voltage noise enabling these filters to achieve a 10,000:1 or better dynamic signal range.

These Filters consist on a four pole high pass filter followed by a four pole low pass filter in one package. The user can select the low pass and high pass filter cutoff frequencies as long as they are not too close to each other. The Q of this filter must remain below 1. For Q's of higher than 1 see our D68BP series of filters. See note 1 below to determine how to calculate the filters Q.

Pretuned to within ±2% of the fixed, user specified center frequency, band-pass D68HPLP filters pass all frequencies lying between the upper and lower -3 dB points of the amplitude response curve.


  • Compact 32-pin footprint minimizes board space requirements.
  • Plug-in ready-to-use, reducing engineering design and manufacturing cycle time.
  • Factory tuned, no external clocks or adjustments needed
  • Broad range of transfer characteristics and corner frequencies to meet a wide range of applications


  • Power line interference rejection
  • Transducer output filtering
  • Production test instrumentation
  • Medical electronics equipment and research
  • Comb filtering and equalization
  • Noise and harmonic analysis
  • RMS measurements
  • Frequency spectrum analysis

Available Band-Pass Models:

D68HPLP 4-pole pair

D68HPLP Series
Fixed Frequency
4-Pole Pair Filters
Model D68HPLP
Product Specifications

Range fo

Available "Q’s"1

1.8" x 0.8" x 0.3"

1 Hz to 100 kHz


Theoretical Transfer
Click to view highpass

Click to view lowpass

Pass-Band Gain
0± 0.2 dB typ.
0± 0.4 dB max.
Attenuation Rate 24 dB/octave
Center Frequency fo     ±2% max.
Stability ±0.01%/°C
Filter Mounting

Notes: 1 Q – Quality Factor for band-pass and band-reject filters. Q = fo / (fH - fL)

fo=sq.rt(fH xX fL)


(@ 25°C and Vs ±15 Vdc)

Analog Input Characteristics (1)
  • Impedance: 10 kΩ min.
  • Voltage Range: ± 10 Vpeak
  • Max. Safe Voltage: ± Vs

Analog Output Characteristics

  • Impedance(Closed Loop):
    1 Ω typ., 10 Ω max.
  • Linear Operating Range: ± 10 V
  • Maximum Current(2): ± 2 mA
  • Offset Voltage(3):
    2 mV typ., 20 mV max.
  • Offset Temp. Coeff.: 50 µV / °C


  1. Input and output signal voltage referenced to supply common.
  2. Output is short circuit protected to common. DO NOT CONNECT TO +/-Vs.
  3. Adjustable to zero.
  4. Units operate with or without offset pin connected.
  5. How to Specify Center Frequency:
    Center frequencies are specified by attaching a three digit frequency designator to the basic model number. Center frequencies can range from 1 Hz to 100 kHz.
Power Supply (+/-Vs)
  • Rated Voltage: ± 15 Vdc
  • Operating Range: ± 5 to ± 18 Vdc
  • Maximum Safe Voltage: ± 18 Vdc
  • Quiescent Current:
    ± 25 mA typ., ± 40 mA max.


  • Operating: 0 to + 70°C
  • Storage: -25 to+85°C

Pin-Out and Package Data

Ordering Information

We hope the information given here will be helpful. The information is based on data and our best knowledge, and we consider the information to be true and accurate. Please read all statements, recommendations or suggestions herein in conjunction with our conditions of sale which apply to all goods supplied by us. We assume no responsibility for the use of these statements, recommendations or suggestions, nor do we intend them as a recommendation for any use which would infringe any patent or copyright.

Frequency Devices, Inc.
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  1784 Chessie Lane
Ottawa, IL 61350

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